Clinical criteria can identify elderly individuals with mild cognitive impairment (MCI). Although MCI is enriched with subjects who have pre-dementia Alzheimer's disease (AD), MCI is clinically heterogeneous. Alzheimer's disease begins in the entorhinal cortex, and imaging entorhinal integrity enhances our ability to detect AD among MCI subjects. MRI can assess entorhinal integrity using two approaches: The first approach relies on structural images to measure entorhinal volume;while the second MRI approach relies on hemodynamic images to estimate entorhinal metabolism. Among different hemodynamic variables, MRI measures of cerebral blood volume (CBV) have proven capable to detect AD-related metabolic dysfunction, including entorhinal dysfunction. The primary goal of this proposal is to determine which MRI measure of entorhinal integrity best detects pre-dementia AD?entorhinal volume, entorhinal metabolism, or perhaps both in combination. In order to achieve this goal we will measure entorhinal volume and entorhinal CBV in a single group of individuals with MCI. We will follow subjects until progression to dementia, and identify which measure of entorhinal integrity best predicts progression to AD. An ancillary goal of this proposal is to follow subjects until autopsy.